The present invention relates to a method for treating a pancreatic disorder. In particular the present invention relates to a method for treating a pancreatic disorder by in vivo administration of a neurotoxin to the body of the pancreas of a patient.
Exocrine Pancreas
The human pancreas is a gland comprised of both exocrine and endocrine tissues. Anatomically, the pancreas consists of unicate process, head, neck, body and tail regions. The acinar cells of the exocrine pancreas secret digestive enzymes, for digesting ingested food. The ductal cells of the exocrine pancreas secret an electrolyte solution comprising bicarbonate for the neutralization of the acidic chyme produced in the stomach. Together the digestive enzymes and the electrolyte fluid make up the pancreatic juice which flows past the sphincter of Oddi into the duodenum via the pancreatic ducts. The exocrine pancreas can make up to three liters per day of pancreatic juice containing about 20 different enzymes and zymogens, such as amylase, lipase, trypsin and trypsinogen. The secretion of pancreatic juice is stimulated by the presence of chyme in the upper portions of the small intestine, and the precise composition of pancreatic juice appears to be influenced by the types of compounds (carbohydrate, lipid, protein, and/or nucleic acid) in the chyme. Gastric acid made by the stomach stimulates the release of secretin. Secretin in turn stimulates the secretion of a pancreatic juice rich in water and electrolytes. Gastric acid, long chain fatty acids and certain amino acids trigger the release of cholecystokinin (CCK) from the duodenum and jejunum. CCK stimulates the secretion of an enzyme rich secretion from the pancreas.
The constituents of pancreatic juice includes proteases (trypsin, chymotrypsin, carboxypolypeptidase), nucleases (RNAse and DNAse), pancreatic amylase, and lipases (pancreatic lipase, cholesterol esterase and phospholipase). Many of these enzymes, including the proteases, are initially synthesized by the acinar cells in an inactive form as zymogens. Thus trypsin is synthesized as trypsinogen, chymotrypsin as chymotypsinogen, and carboxypolypeptidase as procarboxypolypeptidase. These enzymes are activated according to a cascade, wherein, in the first step, trypsin is activated through proteolytic cleavage by the enzyme enterokinase. Trypsinogen can also be autoactivated by trypsin. Once activation has begun, the activation process proceeds rapidly. Trypsin, in turn, activates both chymotypsinogen and procarboxypolypeptidase to form their active protease counterparts.
The exocrine pancreatic enzymes are normally activated only when they enter the intestinal mucosa in order to prevent autodigestion of the pancreas. To prevent premature activation, the acinar cells also co-secrete a trypsin inhibitor that normally prevents activation of the proteolytic enzymes within the secretory cells and in the ducts of the pancreas. Inhibition of trypsin activity also prevents activation of the other proteases.
Pancreatitis is an inflammation of the pancreas and can be chronic or acute. Acute pancreatitis can be edematous or the more severe necrotizing or hemorrhagic pancreatitis. About five thousand new cases of pancreatitis occur each year in the United States and the mortality rate is about ten percent. Pancreatitis is frequently secondary to alcohol abuse or biliary tract disease. Pancreatitis can also be caused by drugs, trauma, gallstones or viral infection. One theory states that pancreatitis is due to autodigestion of the pancreas by proteolytic enzymes activated in the pancreas instead of in the intestinal lumen. Hence, pancreatitis is believed to manifest when an excess amount of trypsin saturates the supply of trypsin inhibitor. Excess trypsin can be due to underproduction of trypsin inhibitor, or the overabundance of trypsin within the cells or ducts of the pancreas. In the latter case, pancreatic trauma or blockage of a duct can lead to localized overabundance of trypsin. Under acute conditions large amounts of pancreatic zymogen secretion can pool in the damaged areas of the pancreas. If even a small amount of free trypsin is available activation of all the zymogenic proteases rapidly occurs, leading to autodigestion of the pancreas and the symptoms of acute pancreatitis. Pancreatitis can be fatal.
Some forms of acute pancreatitis, such as those triggered by excessive use of alcohol, scorpion sting, or intoxication by anti acetylcholine esterase containing insecticides, can be the result of excessive cholinergic stimulation of the exocrine cells of the pancreas. This excessive cholinergic stimulation can result from a symptomatic decrease in the number of pancreatic muscarinic acetylcholine receptors in pancreatitis. Exp Toxicol Pathol April 1994; 45(8): 503-5.
Unfortunately, chronic pancreatitis is believed to be irreversible. Berger et al., The Pancreas, page 720, infra. In Western countries, chronic pancreatitis appears to affect predominantly men aged 25 to 50 years, most of whom are alcoholics.
There are many drawbacks and deficiencies in current therapies for pancreatitis. Treatment of acute pancreatitis can include nasogastric suction to decrease gastrin release from the stomach and thereby prevent gastric contents from entering the duodenum and stimulating pancreatic exocrine secretions. Nasogastric suction is unpleasant and can be ineffective to arrest the course of pancreatitis.
Treatment of chronic pancreatitis can be by surgical resection of from 50% to 95% of the pancreas followed by oral enzyme replacement upon alimentation, clearly a suboptimal form of therapy.
Pancreatitis can be accompanied by constriction of pancreatic ducts leading to the duodenum resulting in a deficiency of pancreatic enzymes in the intestinal lumen, referred to as pancreatic exocrine insufficiency.
Pancreatic exocrine secretion can be regulated by both hormonal and nervous mechanisms. Thus, during the gastric phase of stomach secretion, parasympathetic nerve impulses to the pancreas result in acetylcholinergic stimulation of and release of enzymes by the cholinergically innervated acinar cells.
Significantly, cholinergic innervation dominates neuronal control of the exocrine pancreas. (Berger et al., The Pancreas, volume 1, chapter 5, pages 65-66, Blackwell Science Ltd. (1998), which publication (two volumes) is incorporated herein by reference in its entirety) and it is known that cholinergic stimulation promotes secretion of pancreatic enzymes. Notably, pancreatic acinar cells have acetylcholine receptors. Ibid, pages 83-84. Extrinsic nervous control of the exocrine pancreas is parasympathetic, through vagal input. Ibid, page 66. Intrinsic nervous control of the pancreas refers to that part of the enteric nervous system which is within the pancreas (the intrapancreatic nervous system). The intrapancreatic nervous system comprises an interconnecting plexus of small ganglia supplied by preganglionic vagal fibers and postganglionic sympathetic fibers. Importantly, intrinsic cholinergic neurons (i.e. those with their cell bodies in intrapancreatic ganglia) dominate in the intrapancreatic nervous system. Ibid, page 67.
While intravenous anticholinergics may not significantly influence exocrine pancreatic digestive fluid secretion (see e.g. Dig Dis Sci February 1997; 42(2): 265-72 and Am J Surg January 1996; 171(1): 207-11), extensive literature exists to support the hypothesis of significant cholinergic influence upon exocrine pancreatic cell secretory activity: See e.g. Exp Toxicol Pathol April 1994; 45(8): 503-5, Dig Dis 1992; 10(1):38-45, Dig Dis 1992; 10(6): 326-9, Arch Surg December 1990; 125(12): 1546-9, and Ann Surg April 1982; 195(4): 424-34.
Endocrine Pancreas
The endocrine pancreas comprises the pancreatic islets of Langerhan which are aggregations of polypeptide hormone producing cells scattered widely throughout the acinar tissue and which are most numerous in the tail portion of the pancreas. Typically, total islet tissue constitutes only about 1 or 2 percent of the pancreatic mass.
Islet tissue contains at least three functionally different types of cells: A cells which can make glucagon, B (or .beta.) cells which make insulin and D cells which can make a third islet hormone, somatostatin. The B cells are the most abundant of the three types of islet cells. Insulin promotes the uptake of glucose by cells, especially muscle cells and prevents an excessive breakdown of glycogen stored in liver and muscle. As an antidiabetic hormone essential for lowering blood sugar insulin is a powerful hypoglycemic agent. In most instances, the actions of glucagon are contrary to those of insulin. Thus, glucagon is a hyperglycemic factor which causes blood sugar to increase.
Glucose is the major factor which promotes release of insulin from islet B cells. Glucose also reduces glucagon secretion from islet A cells. Like glucose, glucagon (from islet A cells) also promotes insulin secretion from the islet B cells.
Endocrine pancreatic innervation of the islets of Langerhan is by both sympathetic and parasympathetic nerve fibers which terminate on or near islet cells. Notably, vagal stimulation causes the release of insulin from .beta. cells. Berger et al., The Pancreas, page 110, supra. Thus, stimulation of the dorsal vagus or the pancreatic nerve increases the output of insulin and glucagon and this response is abolished by atropine, a muscarinic acetylcholine receptor antagonist. Additionally, the parasympathetic neurotransmitter acetylcholine stimulates release of insulin from B cells in vivo and in vitro.
Thus, endocrine pancreatic activity appears to be cholinergically influenced since parasympathetic innervation of islet cells can apparently increase insulin secretion, and to a lesser extent, may also increase glucagon secretion. See e.g. Amer J. Physiol July 1999; 277 (1 Pt 1): E93-102, Regul Pept Jun. 3, 1999; 82(1-3): 71-9, J Physiol (Lond) Mar. 1, 1999; 515 (Pt 2): 463-73, Pflugers Arch August 1996; 432(4):589-96, and J Surg Res April 1990; 48(4): 273-8.
Endocrine pancreatic disorders include hypoglycemia (over utilization of glucose) resulting from hyperinsulinism. Hyperinsulinism can be due to an insulinoma. Insulinoma can include single solid tumors, microadenomatosis and islet cell hyperplasia (nesidioblastosis). Additionally, familial hyperinsulinemic hypoglycemia of infancy is due to a gain of function mutation in the sulfonylurea receptor that causes constitutitive, unregulated insulin secretion. The initial treatment for serious hyperglycemia is intravenous administration of 25-50 grams of glucose as a 50% solution. Surgery is the treatment of choice for insulinoma after use of, for example, endoscopic ultrasonography to locate the tumor. Current therapy for an insulinoma if the tumor cannot be located in the pancreas is stepwise pancreatectomy (from tail to head). Resection is stopped with an 85% pancreatectomy, even if the tumor is not found, to avoid a malabsorption problem. Unfortunately, as many as 15% of patients have persistent hypoglycemia, even after surgical resection of the pancreas. Additionally, postoperative complications include acute pancreatitis, peritonitis, fistulas, pseudocyst formation and diabetes mellitus.
Chemotherapy for insulinoma is indicated only in preparation for surgery or after failure to find the tumor at operation. Two drugs are available, diazoxide and octreotide. Unfortunately, because diazoxide has salt retaining properties, it must be accompanied by a diuretic. Additionally, chronic use of octreotide can cause nausea and diarrhea and predispose to cholelithiasis.
botulinum toxin
The anaerobic, gram positive bacterium Clostridium botulinum produces a potent polypeptide neurotoxin, botulinum toxin, which causes a neuroparalytic illness in humans and animals referred to as botulism. The spores of Clostridium botulinum are found in soil and can grow in improperly sterilized and sealed food containers of home based canneries, which are the cause of many of the cases of botulism. The effects of botulism typically appear 18 to 36 hours after eating the foodstuffs infected with a Clostridium botulinum culture or spores. The botulinum toxin can apparently pass unattenuated through the lining of the gut and attack peripheral motor neurons. Symptoms of botulinum toxin intoxication can progress from difficulty walking, swallowing, and speaking to paralysis of the respiratory muscles and death.
botulinum toxin type A is the most lethal natural biological agent known to man. About 50 picograms of botulinum toxin (purified neurotoxin complex) type A is a LD.sub.50 in mice. One unit (U) of botulinum toxin is defined as the LD.sub.50 upon intraperitoneal injection into female Swiss Webster mice weighing 18-20 grams each. Seven immunologically distinct botulinum neurotoxins have been characterized, these being respectively botulinum neurotoxin serotypes A, B, C.sub.1, D, E, F and G each of which is distinguished by neutralization with type-specific antibodies. The different serotypes of botulinum toxin vary in the animal species that they affect and in the severity and duration of the paralysis they evoke. For example, it has been determined that botulinum toxin type A is 500 times more potent, as measured by the rate of paralysis produced in the rat, than is botulinum toxin type B. Additionally, botulinum toxin type B has been determined to be non-toxic in primates at a dose of 480 U/kg which is about 12 times the primate LD.sub.50 for botulinum toxin type A. botulinum toxin apparently binds with high affinity to cholinergic motor neurons, is translocated into the neuron and blocks the release of acetylcholine.
botulinum toxins have been used in clinical settings for the treatment of neuromuscular disorders characterized by hyperactive skeletal muscles. botulinum toxin type A has been approved by the U.S. Food and Drug Administration for the treatment of blepharospasm, strabismus and hemifacial spasm. Non-type A botulinum toxin serotypes apparently have a lower potency and/or a shorter duration of activity as compared to botulinum toxin type A. Clinical effects of peripheral intramuscular botulinum toxin type A are usually seen within one week of injection. The typical duration of symptomatic relief from a single intramuscular injection of botulinum toxin type A averages about three months.
Although all the botulinum toxins serotypes apparently inhibit release of the neurotransmitter acetylcholine at the neuromuscular junction, they do so by affecting different neurosecretory proteins and/or cleaving these proteins at different sites. For example, botulinum types A and E both cleave the 25 kiloDalton (kD) synaptosomal associated protein (SNAP-25), but they target different amino acid sequences within this protein. botulinum toxin types B, D, F and G act on vesicle-associated protein (VAMP, also called synaptobrevin), with each serotype cleaving the protein at a different site. Finally, botulinum toxin type C.sub.1 has been shown to cleave both syntaxin and SNAP-25. These differences in mechanism of action may affect the relative potency and/or duration of action of the various botulinum toxin serotypes. Significantly, it is known that the cytosol of pancreatic islet B cells contains at least SNAP-25 (Biochem J 1;339 (pt 1): 159-65 (April 1999)), and synaptobrevin (Mov Disord May 1995; 10(3): 376).
With regard to the use of a botulinum toxin to treat a pancreatic related disorder, it is known to treat a form of pancreatitis by injecting a botulinum toxin into the minor duodenal papilla (because of the proximity of the minor papilla to the pancreatic duct) to thereby relax a constricted pancreatic duct (pancreatic divisum) and increase the flow of pancreatic juice through the pancreatic duct into the duodenum. Gastrointest Endosc October 1999; 50 (4): 545-548.
The molecular weight of the botulinum toxin protein molecule, for all seven of the known botulinum toxin serotypes, is about 150 kD. Interestingly, the botulinum toxins are released by Clostridial bacterium as complexes comprising the 150 kD botulinum toxin protein molecule along with associated non-toxin proteins. Thus, the botulinum toxin type A complex can be produced by Clostridial bacterium as 900 kD, 500 kD and 300 kD forms. botulinum toxin types B and C.sub.1 is apparently produced as only a 500 kD complex. Botulinum toxin type D is produced as both 300 kD and 500 kD complexes. Finally, botulinum toxin types E and F are produced as only approximately 300 kD complexes. The complexes (i.e. molecular weight greater than about 150 kD) are believed to contain a non-toxin hemaglutinin protein and a non-toxin and non-toxic nonhemaglutinin protein. These two non-toxin proteins (which along with the botulinum toxin molecule comprise the relevant neurotoxin complex) may act to provide stability against denaturation to the botulinum toxin molecule and protection against digestive acids when toxin is ingested. Additionally, it is possible that the larger (greater than about 150 kD molecular weight) botulinum toxin complexes may result in a slower rate of diffusion of the botulinum toxin away from a site of intramuscular injection of a botulinum toxin complex.
In vitro studies have indicated that botulinum toxin inhibits potassium cation induced release of both acetylcholine and norepinephrine from primary cell cultures of brainstem tissue. Additionally, it has been reported that botulinum toxin inhibits the evoked release of both glycine and glutamate in primary cultures of spinal cord neurons and that in brain synaptosome preparations botulinum toxin inhibits the release of each of the neurotransmitters acetylcholine, dopamine, norepinephrine, CGRP and glutamate.
botulinum toxin type A can be obtained by establishing and growing cultures of Clostridium botulinum in a fermenter and then harvesting and purifying the fermented mixture in accordance with known procedures. All the botulinum toxin serotypes are initially synthesized as inactive single chain proteins which must be cleaved or nicked by proteases to become neuroactive. The bacterial strains that make botulinum toxin serotypes A and G possess endogenous proteases and serotypes A and G can therefore be recovered from bacterial cultures in predominantly their active form. In contrast, botulinum toxin serotypes C.sub.1, D and is E are synthesized by nonproteolytic strains and are therefore typically unactivated when recovered from culture. Serotypes B and F are produced by both proteolytic and nonproteolytic strains and therefore can be recovered in either the active or inactive form. However, even the proteolytic strains that produce, for example, the botulinum toxin type B serotype only cleave a portion of the toxin produced. The exact proportion of nicked to unnicked molecules depends on the length of incubation and the temperature of the culture. Therefore, a certain percentage of any preparation of, for example, the botulinum toxin type B toxin is likely to be inactive, possibly accounting for the known significantly lower potency of botulinum toxin type B as compared to botulinum toxin type A. The presence of inactive botulinum toxin molecules in a clinical preparation will contribute to the overall protein load of the preparation, which has been linked to increased antigenicity, without contributing to its clinical efficacy. Additionally, it is known that botulinum toxin type B has, upon intramuscular injection, a shorter duration of activity and is also less potent than botulinum toxin type A at the same dose level.
It has been reported that botulinum toxin type A has been used in clinical settings as follows:
(1) about 75-125 units of BOTOX.RTM..sup.1 per intramuscular injection (multiple muscles) to treat cervical dystonia; PA1 (2) 5-10 units of BOTOX.RTM. per intramuscular injection to treat glabellar lines (brow furrows) (5 units injected intramuscularly into the procerus muscle and 10 units injected intramuscularly into each corrugator supercilii muscle); PA1 (3) about 30-80 units of BOTOX.RTM. to treat constipation by intrasphincter injection of the puborectalis muscle; PA1 (4) about 1-5 units per muscle of intramuscularly injected BOTOX.RTM. to treat blepharospasm by injecting the lateral pre-tarsal orbicularis oculi muscle of the upper lid and the lateral pre-tarsal orbicularis oculi of the lower lid. PA1 (5) to treat strabismus, extraocular muscles have been injected intramuscularly with between about 1-5 units of BOTOX.RTM., the amount injected varying based upon both the size of the muscle to be injected and the extent of muscle paralysis desired (i.e. amount of diopter correction desired). PA1 (6) to treat upper limb spasticity following stroke by intramuscular injections of BOTOX.RTM. into five different upper limb flexor muscles, as follows:
 FNT .sup.1 Available from Allergan. Inc., of Irvine, Calif. under the tradename BOTOX.RTM..
(a) flexor digitorum profundus: 7.5 U to 30 U PA2 (b) flexor digitorum sublimus: 7.5 U to 30 U PA2 (c) flexor carpi ulnaris: 10 U to 40 U PA2 (d) flexor carpi radialis: 15 U to 60 U PA2 (e) biceps brachii: 50 U to 200 U. Each of the five indicated muscles has been injected at the same treatment session, so that the patient receives from 90 U to 360 U of upper limb flexor muscle BOTOX.RTM. by intramuscular injection at each treatment session.
The success of botulinum toxin type A to treat a variety of clinical conditions has led to interest in other botulinum toxin serotypes. A study of two commercially available botulinum type A preparations (BOTOX.RTM. and Dysport.RTM.) and preparations of botulinum toxins type B and F (both obtained from Wako Chemicals, Japan) has been carried out to determine local muscle weakening efficacy, safety and antigenic potential. botulinum toxin preparations were injected into the head of the right gastrocnemius muscle (0.5 to 200.0 units/kg) and muscle weakness was assessed using the mouse digit abduction scoring assay (DAS). ED.sub.50 values were calculated from dose response curves. Additional mice were given intramuscular injections to determine LD.sub.50 doses. The therapeutic index was calculated as LD.sub.50 /ED.sub.50. Separate groups of mice received hind limb injections of BOTOX.RTM. (5.0 to 10.0 units/kg) or botulinum toxin type B (50.0 to 400.0 units/kg), and were tested for muscle weakness and increased water consumption, the later being a putative model for dry mouth. Antigenic potential was assessed by monthly intramuscular injections in rabbits (1.5 or 6.5 ng/kg for botulinum toxin type B or 0.15 ng/kg for BOTOX.RTM.). Peak muscle weakness and duration were dose related for all serotypes. DAS ED.sub.50 values (units/kg) were as follows: BOTOX.RTM.: 6.7, Dysport.RTM.: 24.7, botulinum toxin type B: 27.0 to 244.0, botulinum toxin type F: 4.3. BOTOX.RTM. had a longer duration of action than botulinum toxin type B or botulinum toxin type F. Therapeutic index values were as follows: BOTOX.RTM.: 10.5, Dysport.RTM.: 6.3, botulinum toxin type B: 3.2. Water consumption was greater in mice injected with botulinum toxin type B than with BOTOX.RTM., although botulinum toxin type B was less effective at weakening muscles. After four months of injections 2 of 4 (where treated with 1.5 ng/kg) and 4 of 4 (where treated with 6.5 ng/kg) rabbits developed antibodies against botulinum toxin type B. In a separate study, 0 of 9 BOTOX.RTM. treated rabbits demonstrated antibodies against botulinum toxin type A. DAS results indicate relative peak potencies of botulinum toxin type A being equal to botulinum toxin type F, and botulinum toxin type F being greater than botulinum toxin type B. With regard to duration of effect, botulinum toxin type A was greater than botulinum toxin type B, and botulinum toxin type B duration of effect was greater than botulinum toxin type F. As shown by the therapeutic index values, the two commercial preparations of botulinum toxin type A (BOTOX.RTM. and Dysport.RTM.) are different. The increased water consumption behavior observed following hind limb injection of botulinum toxin type B indicates that clinically significant amounts of this serotype entered the murine systemic circulation. The results also indicate that in order to achieve efficacy comparable to botulinum toxin type A, it is necessary to increase doses of the other serotypes examined. Increased dosage can comprise safety. Furthermore, in rabbits, type B was more antigenic than was BOTOX.RTM., possibly because of the higher protein load injected to achieve an effective dose of botulinum toxin type B.
Acetylcholine
Typically only a single type of small molecule neurotransmitter is released by each type of neuron in the mammalian nervous system. The neurotransmitter acetylcholine is secreted by neurons in many areas of the brain, but specifically by the large pyramidal cells of the motor cortex, by several different neurons in the basal ganglia, by the motor neurons that innervate the skeletal muscles, by the preganglionic neurons of the autonomic nervous system (both sympathetic and parasympathetic), by the postganglionic neurons of the parasympathetic nervous system, and by some of the postganglionic neurons of the sympathetic nervous system. Essentially, only the postganglionic sympathetic nerve fibers to the sweat glands, the piloerector muscles and a few blood vessels are cholinergic and most of the postganglionic neurons of the sympathetic nervous system secret the neurotransmitter norepinephine. In most instances acetylcholine has an excitatory effect. However, acetylcholine is known to have inhibitory effects at some of the peripheral parasympathetic nerve endings, such as inhibition of the heart by the vagal nerve.
The efferent signals of the autonomic nervous system are transmitted to the body through either the sympathetic nervous system or the parasympathetic nervous system. The preganglionic neurons of the sympathetic nervous system extend from preganglionic sympathetic neuron cell bodies located in the intermediolateral horn of the spinal cord. The preganglionic sympathetic nerve fibers, extending from the cell body, synapse with postganglionic neurons located in either a paravertebral sympathetic ganglion or in a prevertebral ganglion. Since, the preganglionic neurons of both the sympathetic and parasympathetic nervous system are cholinergic, application of acetylcholine to the ganglia will excite both sympathetic and parasympathetic postganglionic neurons.
Acetylcholine activates two types of receptors, muscarinic and nicotinic receptors. The muscarinic receptors are found in all effector cells stimulated by the postganglionic neurons of the parasympathetic nervous system, as well as in those stimulated by the postganglionic cholinergic neurons of the sympathetic nervous system. The nicotinic receptors are found in the synapses between the preganglionic and postganglionic neurons of both the sympathetic and parasympathetic. The nicotinic receptors are also present in many membranes of skeletal muscle fibers at the neuromuscular junction.
Acetylcholine is released from cholinergic neurons when small, clear, intracellular vesicles fuse with the presynaptic neuronal cell membrane. A wide variety of non-neuronal secretory cells, such as, adrenal medulla (as well as the PC12 cell line) and pancreatic islet cells release catecholamines and insulin, respectively, from large dense-core vesicles. The PC12 cell line is a clone of rat pheochromocytoma cells extensively used as a tissue culture model for studies of sympathoadrenal development. botulinum toxin inhibits the release of both types of compounds from both types of cells in vitro, permeabilized (as by electroporation) or by direct injection of the toxin into the denervated cell. botulinum toxin is also known to block release of the neurotransmitter glutamate from cortical synaptosomes cell cultures.
What is needed therefore is an effective, long lasting, non-surgical resection, non-radiotherapy therapeutic method for treating exocrine pancreatic disorders such as pancreatitis and endocrine pancreatic disorders such as hyperinsulinism.